The effects of pulsed electromagnetic fields combined with a static magnetic intramedullary implant on the repair of bone defects: A preliminary study

There is a basic consensus on the biological effects of pulsed electromagnetic fields (PEMFs) on bone formation and bone reconstruction. PEMFs have been widely used in clinical treatment of osteoporosis, bone nonunion and delayed fracture healing. PEMFs is an intervention method of physiotherapy in vitro. In order to optimize the effect of PEMFs intervention, this study combined with the orthopedics clinic to construct a static magnetic intramedullary implant using NdFeB magnets as components. At the same time, it combines external-pulsed electromagnetic field to achieve locally targeted magnetic microenvironment. Rabbits were randomly divided into a combined magnetic field group (Implantation of static magnetic intramedullary implant in vivo combined with external-pulsed electromagnetic field), pulsed electromagnetic field group and control group. Micro CT and histopathology were used to estimate the effect of each group on bone formation and reconstruction in the early stage (5 weeks) of bone defect repair. Our data showed that the combined magnetic field group had relatively better new bone volume and trabecular structure in the bone defect area. The results showed that the combined magnetic field intervention method was feasible and had relatively preferably osteogenesis promoting effect. This study provides a new idea of magnetic field intervention, and also preliminarily verifies the feasibility of adding magnetic field to traditional orthopedic implant materials. However, the magnetic field strength of implanted materials still needs to be further refined.